Telephone



UNiTED STATES PATENT OFFICE.

FREDERICK K. FITCH, OF JERSEY CITY, NEW JERSEY.

TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 244,442, dated July 19, 1881.

Application tiled September 30, 1880. (No model.)

To all 'whom it may concern:

Beit known that I, FREDERICK K. FrrcH, a citizen of Jersey City, residing at Jersey City, in the county ot' Hudson and State of New Jersey, have invented certain new and useful Improvements in Telephones 5 and I do hereby declare the following to be a full, clear, and exact description of the invention,.such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters or figures of reference marked thereon, which form a part. of this specification, in which- Figure lis a side elevation of my invention. Fig. 2 is a rear elevation.

This invention has relation to magneto-electric telephones, or that class in which the diaphragm is vibrated under the iniiuence of an electro-magnet.

My invention relates specially to the receiving-instrument now generally used in circuit with a carbon or battery telephone.

The object of my invention is to provide an instrument which shall be delicately sensitive, and responsive in the highest degree to the electric and magnetic variations by which it is influenced, and which, moreover, shall re-enforce and amplify the resultant mechanical vibrations, so as to intensify the sound effects and render the lreceiver a clearer and louder talker7 than it has hitherto been made.

My invention accordingly consists, first, in the substitution for the form of electro-magnet now employed of what is generally known as the Siemens77 magnet, in which a pair ofv elec, tro -magnets or coils having soft iron cores are superposed upon a permanently magnetic base, or rather upon one pole thereof, while the other pole is curved or continued upward, and is provided with a pivoted tongue or armature which vibrates between the projecting cores ofthe two coils. This tongue is of sott iron, -and has the same magnetic polarity as the end of the magnet to which it is attached. When the Siemens magnet is not under the inuence of a current of electricity the tongue or armature will adhere to whichever core of the respective coils it happens to touch, the cores 5o being ofthe same polarity and of equal attractive powers. Now,if a current of electricity be sent through the coilswhich are in circuit in one direction, or of a given polarity, one of the cores will have the magnetism increased while the magnet-ism of the other core will be destroyed or rendered ot' lesser intensity. For instance, supposing that the cores rest on the' north pole of the permanent magnet, they will then be both ot' north polarity by induction. Now, it' the current be one ofthe poles will have its normal magnetism increased,

while that of the other pole will be canceled, the tongue or armature being of south polarity will be attracted by and toward the re-enforced core. It' the current be reversed, then the other core becomes and the lirst whereupon the tongue is attracted in the opposite direction. The Siemens magnet isa very sensitive instrument, and has been found responsive to the most delicate currents. The slightest disturbance of the normal magnetic equilibrium is sufficient to give the armature an impulse in the direction to which the re-enforcement calls it, the weight of the armature being compensated for by the permanent magnetism of the core to which it is directed, and the attracting magnetism being expended in directive Work only. I have discovered that such a magnet and armature may be made available for telephonie purposes, and that the constantly-changing directions of the electric current may be made thereby to impart positive motion in alternating direction to the armature, and through it to the diaphragm of a receiving-telephone, instead of a positive motion. in one direction and a negative or repulsive movement in the other, as occurs with the ordinary or Bell telephone under its original or hitherto modified and improved form. Where the diaphragm is opposed to the ends of the electro-magnetic cores or poles, as in the c Bell telephone and its modifications, the only force which is positively active is that which tends to attract the diaphragm. In theory there is a repulsive force tending to repel the diaphragm under a reversal ot' current, but this force is in practice weak and impotent, and hence the reaction of the diaphragm is mainly dependent upon the elasticity of the metal of which it is composed. I do not find IOO that such reaction is equal or commensurate with the counter magnetic attraction or the latent powers of the reversed current, and I regard this inequality as one of the causes of indistinctness and imperfection in the articulation of the receiving-telephones in use, and itL must be obvious that it greatly interferes with the loudness and intensity of sound which the instrument is capable ot' giving forth. By using the Siemens magnet or au equivalent polarized couple, and properly disposing the diaphragm, I do not depend upon the comparatively weak retractileelasticity, orthe still more powerless repelling` magnetism to move the diaphragm in one direction, but I cause the movement to follow and positively respond to the magnetic variations equally iu either direction, and thus fully resolve the electrical undulations into sound.

Myinvention consists, secondly, in a method and means of amplifying the vibrations ofthe diaphragm so as to increase its eifectiveness. This I accomplish by locating the diaphragm at the end of an elongated armature playing between the cores of the polarized or Siemens magnet. The pivotal point of the armature is on aline midway between the cores and the diaphragm at the other end, hence the play or vibration of the diaphragm end will be greater than the play of the armature between the cores, so that very minute vibrations at the latter point will be productive of enlarged or am plied "ibrations in the neighborhood of the diaphragm through the mechanical agency and leverage of the armature, and the result will be au increase in loudness of tone far beyond the possibilities of aninstrumentin which the diaphragm is directly opposite and faces the magnetic cores.

The accompanying drawings illustrate the means of carrying my invention into effect.

A designates the diaphragm, ot' any suitable character. Under the conditions of my invention this diaphragm may be made larger and thicker than those now in use, so as to adapt it to the enlarged vibrations which it is called upon to perform. The diaphragm and other parts of the instruments are inclosed, as usual, in a suitable box or case, which need not be described.

B represents the electro-magnet, which is, in general construction, the same as the wellknown Siemens polarized relay, the two coils having respectively right-and-left hand wind- 1n gs.

C is thc vibrating tongue or armature, pivoted, as shown, to one leg or pole ot' the permanent magnet D, whereon the electric coils and cores rest, and arranged between the two cores. The cores are provided with inwardly 1' ro]'ecting or converging extensions, E, which limit the play of the tongue and bringit more fully within the magnetic influence. These extensions are adjustable toward each other, so as to admit of the requisite regulation, and may be padded opposite the armature with any suitable material, or the tongueitselt' may be padded instead, the object being to destroy the click,77 which would be otherwise appreciable. The diaphragm is permanently attached at its center to the free end of the tongue and on a plane at right angles to the line ot' intersection of the two cores. Now, as the incoming currents of' electricity will be alternately and thc tongue will be corrcspondingly vibrated, but with a positive motion in either direction, and the diaphragm will partake of the same movement or vibration. 'lhe amplitude of the vibrations of the diaphragm will depend upon the length of the tongue. v

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is-

l. A telephonie instrument comprising a polarized relay and a diaphragm, the latter being attached at its center to the tongue of the relay, substantially as set forth.

2. The combination, with a polarized or Siemens relay or electro-magnet, of a diaphragm arranged substantially as described, whereby it will respond positively to the inuence of currents in either direction.

In testimony whereof I atix my signature in presence of two witnesses.

FREDERICK K. FITCH.

Witnesses:

GEO. B. WAL'roN, J. T. MURRAY. 

